As this type of conventional steering lock device, there is one disclosed in Japanese Patent Laid-Open Publication No. 2009-248843 (Patent Literature 1). As shown in FIG. 1, this steering lock device 100 includes: a lock member 102 that is urged in a direction (upward direction of FIG. 1) of a steering shaft (not shown) of an automobile by a coiled spring 101, and is fittable to the steering shaft; a drive body 103 that drives this lock member 102; and an auxiliary lock mechanism 120 that is arranged in the vicinity of the lock member 102, and is capable of locking the lock member 102 at a steering lock position. Moreover, the drive body 103 includes: a rotation member 106 to be driven by a motor 105 through a worm (not shown); and a cam member 107 that moves reciprocally in a moving direction of the lock member 102 by rotation of this rotation member 106, and this cam member 107 is coupled to the lock member 102 through a coupling pin 108. The auxiliary lock mechanism 120 is composed of a slide plate 104, a holding shaft 113, spring members 111a and 111b, and a holding member 115.
The slide plate 104 includes an engagement projection 110 capable of engaging with an engagement groove 109 of a side portion of the lock member 102, and is urged in a direction of the lock member 102 by the spring member 111a. Moreover, the holding shaft 113 is extended from a back surface of a frame cover 112 along the moving direction of the lock member 102 toward the slide plate 104. A tip end portion 113a of this holding shaft 113 engages with an engagement groove portion 114 of the slide plate 104, whereby the slide plate 104 is kept in a state of being spaced apart from the lock member 102.
By the spring member 111a, the holding shaft 113 is urged in a direction of being spaced apart from the slide plate 104. Moreover, an engagement pin 116 is extended from the holding member 115 detachably fitted into the back surface of the frame cover 112. A tip end of this engagement pin 116 engages with a rear end portion 113b of the holding shaft 113, whereby a state where the holding shaft 113 engages with the slide plate 104 is kept.
In the above-described configuration, when the motor 105 is rotated in a lock direction at the time of parking, the rotation member 106 rotates by drive force of the motor 105, and the cam member 107 moves in the lock direction (upward direction of FIG. 1) of the lock member 102. Therefore, the lock member 102 positionally shifts to the steering lock position by urging force of the coiled spring 101. As a result, a tip end of the lock member 102 fits to the steering shaft, and rotation of the steering shaft is inhibited, and accordingly, the automobile turns to an unsteerable state.
Thereafter, when the motor 105 is rotated in a lock release direction, the rotation member 106 rotates in a reverse direction, and the lock member 102 positionally shifts to a lock release position together with the cam member 107. As a result, the fitting of the lock member 102 to the steering shaft is released, accordingly, the rotation of the steering shaft becomes free, and the automobile turns to a steerable state.
Moreover, in such a lock state shown in FIG. 1, the holding shaft 113 protrudes from the back surface of the frame cover 112 toward the slide plate 104, and a tip end thereof engages with the engagement groove portion 114 of the slide plate 104. In such a way, the slide plate 104 is kept in a state of being spaced apart from the lock member 102.
Subsequently, in the case where external force is applied to the steering lock device 100 from the frame cover 112 side at the time of parking such a vehicle by an illegal unlocking action, the holding member 115 falls off from the back surface of the frame cover 112, and moves a tapered portion 112a. In such a way, the engagement between the engagement pin 116 and the holding shaft 113 is disengaged, the holding shaft 113 moves to the frame cover 12 side, and the holding shaft 113 separates from the engagement groove portion 114 of the slide plate 104. Therefore, the slide plate 104 is urged in the direction of the lock member 102 by the spring member 111a, and the engagement projection 110 engages with the engagement groove 109 of the side portion of the lock member 102. In such a way, the lock member 102 is stopped at the steering lock position, accordingly, the rotation of the steering shaft is inhibited, a malfunction that the vehicle becomes steerable by an illegal lock release operation can be prevented, and stealing-proof of the vehicle at the time of parking the vehicle can be enhanced.